This invention relates to a weighing apparatus and method for determining the weight of a load while the load is in motion. The invention permits the contents of a refuse container, for example a "roll-out" refuse container, to be quickly weighed with extreme accuracy while the container is being emptied. The disclosure of this application relates specifically to weighing of refuse in a refuse container, but has many other applications.
Typical roll-out refuse collection takes place by driving a collection truck along a collection route. On specified days residents roll wheeled containers to be emptied to the street.
Collection workers move the curbside containers onto a lift unit carried by the truck. Upon actuation the lift unit moves the container vertically and horizontally through a range of motion while inverting the container into the truck hopper. The lift operator may "bang" the container at the top of the cycle to dislodge contents The lift unit is reversed and the container lowered. The container is removed from the lift unit. The truck moves to the next container and the process is repeated.
In commercial and industrial environments, special trucks empty the containers from and return the empty containers to their usual position.
While the term "refuse container" is used throughout this application, the term is used in its broad sense to mean many types of containers such as recycling containers, drums and similar products. The term "contents" is used to refer to what is emptied from the refuse containers, whether "refuse" in the strict sense, or recycling materials or other material.
Recent recognition of the importance of recycling and the expense of disposing of household and business refuse have created a demand for more up-to-date methods and practices of refuse collection and disposal. Some municipalities and business concerns have begun instituting programs to encourage conservation and recycling by charging for refuse collection and paying for recyclables based upon the weight collected for disposal. So far as is known, some systems for doing this are in development and are believed to involve raising a refuse container off of the ground, stopping the lifter to permit the container to achieve a state of equilibrium necessary to factor out inertia, momentum, acceleration and similar phenomena, weighing the container, emptying the contents, and either subtracting from the measured weight of the container an assumed standard weight of an empty container, or repeating the process of bringing the container to a stop during lowering of the container to obtain an empty weight while the container is in an equilibrium condition.
There are difficulties with both of the above approaches. Merely subtracting a standard empty container weight from the loaded weight does not take into account that in many instances some refuse may be left in the container because of jamming or sticking and not emptied When this happens, the customer is charged for refuse not collected at each collection for as long as the stuck refuse remains in the container, as well as when the refuse is later actually emptied.
Weighing the container while lifting and again while lowering takes into account refuse which may be left in the container. However, bringing the container to a stop twice during each cycle greatly increases the time required to empty a container and hence the efficiency of the entire process. Furthermore, it is believed that conventional weighing devices and processes cannot accurately compensate for the wide range of dynamic conditions which are necessarily encountered along a refuse collection route.
There are other considerations as well. Since a customer is being charged based on the weight of the contents being emptied, it is important to accurately associate a particular container with a particular account--typically a residence or business address. In order to maintain efficiency and to accommodate typical skill levels applicable to refuse collection workers, it is important to make as much of the weighing and container identification process and subsequent matching of data automatic and therefore transparent to the collection workers.
The invention described in this application addresses these problems by use of technology which provides reliability, extremely accurate results, durability even under extreme weather and use conditions, and operation which, from the operator vantage point, is the same as conventional emptying without weighing.